This introduction offers a summary of the antecedents, goals, and prospects of the present volume. On the one hand, it emphasizes the important role of this collection of papers. It’s the first attempt to provide a global characterization of the syntactic variation of Spanish dialects. This is a very rich, but largely unexplored, area of inquiry, a situation that is probably due to a combination of various factors: lack of theoretical tools, interest in more easily observable (lexical, phonetic, or morphological) differences, etc. On the other hand, it introduces chapters that show varying and complementary formal approaches to the study of the syntactic phenomena of both American Spanish and European Spanish dialects.